Current-voltage convertor, reference voltage generator and non-volatile semiconductor storage device

Abstract

A stable reference voltage that can be supplied in a layout area smaller than prior art is provided. A current-voltage convertor includes a first current mirror circuit including a first MOS transistor, a second MOS transistor in a pair, and an output resistor; and a depletion type N-channel MOS transistor, inserted between a first voltage to be input and the first MOS transistor and the second MOS transistor, and having a gate to which an output voltage from the output resistor is fed back. When a reference current is input to the first MOS transistor, the output voltage is generated by a current corresponding to the reference current flowing into the second MOS transistor and the output resistor. In addition, a reference voltage generator including the current-voltage convertor is provided to output a reference voltage based on the output voltage of the current-voltage convertor.

What is claimed is: 
     
       1. A current-voltage convertor, comprising:
 a first current mirror circuit, comprising a first metal-oxide semiconductor transistor and a second metal-oxide semiconductor transistor in a pair, and an output resistor; 
 a depletion type N-channel metal-oxide semiconductor transistor, inserted between a first voltage as input and the pair of the first metal-oxide semiconductor transistor and the second metal-oxide semiconductor transistor, 
 when a reference current is input to the first metal-oxide semiconductor transistor, a first output voltage is generated by a current corresponding to the reference current via the second metal-oxide semiconductor transistor and the output resistor, and the first output voltage is connected to a gate of the depletion type N-channel metal-oxide semiconductor transistor; 
 a third metal-oxide semiconductor transistor, inserted between the second metal-oxide semiconductor transistor and the output resistor, and having a gate and a drain connected to each other; and 
 a fourth metal-oxide semiconductor transistor, clamping a second voltage based on the first output voltage, wherein 
 the third metal-oxide semiconductor transistor and the fourth metal-oxide semiconductor transistor are configured as a second current mirror circuit, and 
 a reference voltage is output based on a second output voltage from the fourth metal-oxide semiconductor transistor. 
 
     
     
       2. A reference voltage generator, comprising the current-voltage convertor according to  claim 1 , wherein the reference voltage generator is configured to:
 output a reference voltage based on the second output voltage of the current-voltage convertor. 
 
     
     
       3. The reference voltage generator according to  claim 1 , further comprising: a source follower circuit, supplying the second output voltage, and being connected to a source of the fourth metal-oxide semiconductor transistor to make a predetermined current flow. 
     
     
       4. A non-volatile semiconductor storage device comprising a memory array, wherein the non-volatile semiconductor storage device comprises:
 the reference voltage generator according to  claim 1 , wherein 
 the second output voltage from the reference voltage generator is supplied to the memory array of the non-volatile semiconductor storage device. 
 
     
     
       5. A non-volatile semiconductor storage device comprising a memory array, wherein the non-volatile semiconductor storage device comprises:
 the reference voltage generator according to  claim 2 , wherein 
 the second output voltage from the reference voltage generator is supplied to the memory array of the non-volatile semiconductor storage device. 
 
     
     
       6. The reference voltage generator according to  claim 3 , wherein the source follower circuit comprises a fifth metal-oxide semiconductor transistor having a gate forced to a predetermined bias voltage. 
     
     
       7. A non-volatile semiconductor storage device comprising a memory array, wherein the non-volatile semiconductor storage device comprises:
 the reference voltage generator according to  claim 3  wherein 
 the second output voltage from the reference voltage generator is supplied to the memory array of the non-volatile semiconductor storage device. 
 
     
     
       8. A non-volatile semiconductor storage device comprising a memory array, wherein the non-volatile semiconductor storage device comprises:
 the reference voltage generator according to  claim 6  wherein 
 the second output voltage from the reference voltage generator is supplied to the memory array of the non-volatile semiconductor storage device.